Enhanced selective nitroarene hydrogenation over Au supported on β-Mo2C and β-Mo2C/Al2O3

Noémie Perret, Xiaodong Wang, Laurent Delannoy, Claude Potvin, Catherine Louis, Mark Keane

Research output: Contribution to journalArticle

50 Citations (Scopus)

Abstract

β-Mo2C and β-Mo2C/Al2O3 have been synthesised via temperature programmed carburisation and employed, for the first time, as supports for gold catalysts. 1% w/w Au/Mo2C and Au/Mo2C/Al2O3 were prepared by deposition–precipitation with urea and used to promote the gas phase hydrogenation of para-chloronitrobenzene (p-CNB) and meta-dinitrobenzene (m-DNB) where 1% w/w Au/Al2O3 served as a reference catalyst. The supports and supported Au catalysts have been characterised in terms of point of zero charge, temperature programmed reduction (TPR), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) measurements. Both Mo2C and Mo2C/Al2O3 exhibited hydrogenation activity that was significantly enhanced with the incorporation of Au. XPS and elemental analysis of Mo2C/Al2O3 revealed a lesser carbidic character and the presence of free surface carbon. Moreover, preparation of Au/Mo2C/Al2O3 was accompanied by a leaching of the Mo component into solution. The carbide-based catalysts were characterised by a broader distribution of larger Au particles compared with the reference Au/Al2O3, which can be attributed to weaker Au/carbide interactions resulting in Au agglomeration during synthesis and activation. Nevertheless, the carbide systems delivered higher hydrogenation rates relative to Au/Al2O3. All the Au catalysts tested exhibited 100% selectivity to the target p-chloroaniline product in p-CNB hydrogenation. In the case of m-DNB, both nitro groups were hydrogenated to generate m-phenylenediamine as principal product for reaction over Au/Al2O3 whereas Au/Mo2C promoted the exclusive production of m-nitroaniline at low conversions. The results demonstrate a synergistic effect between Au and Mo2C that can be exploited in the cleaner production of commercially important aromatic amines.
Original languageEnglish
Pages (from-to)172-183
Number of pages12
JournalJournal of Catalysis
Volume286
Early online date6 Dec 2011
DOIs
Publication statusPublished - Feb 2012

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1-chloronitrobenzene
Hydrogenation
hydrogenation
Catalyst supports
Carbides
catalysts
Catalysts
carbides
X ray photoelectron spectroscopy
Catalyst selectivity
photoelectron spectroscopy
cleaners
Urea
x rays
Gold
X ray powder diffraction
Leaching
Amines
leaching
products

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Enhanced selective nitroarene hydrogenation over Au supported on β-Mo2C and β-Mo2C/Al2O3. / Perret, Noémie; Wang, Xiaodong; Delannoy, Laurent; Potvin, Claude; Louis, Catherine; Keane, Mark.

In: Journal of Catalysis, Vol. 286, 02.2012, p. 172-183.

Research output: Contribution to journalArticle

Perret, Noémie ; Wang, Xiaodong ; Delannoy, Laurent ; Potvin, Claude ; Louis, Catherine ; Keane, Mark. / Enhanced selective nitroarene hydrogenation over Au supported on β-Mo2C and β-Mo2C/Al2O3. In: Journal of Catalysis. 2012 ; Vol. 286. pp. 172-183.
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AU - Keane, Mark

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N2 - β-Mo2C and β-Mo2C/Al2O3 have been synthesised via temperature programmed carburisation and employed, for the first time, as supports for gold catalysts. 1% w/w Au/Mo2C and Au/Mo2C/Al2O3 were prepared by deposition–precipitation with urea and used to promote the gas phase hydrogenation of para-chloronitrobenzene (p-CNB) and meta-dinitrobenzene (m-DNB) where 1% w/w Au/Al2O3 served as a reference catalyst. The supports and supported Au catalysts have been characterised in terms of point of zero charge, temperature programmed reduction (TPR), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) measurements. Both Mo2C and Mo2C/Al2O3 exhibited hydrogenation activity that was significantly enhanced with the incorporation of Au. XPS and elemental analysis of Mo2C/Al2O3 revealed a lesser carbidic character and the presence of free surface carbon. Moreover, preparation of Au/Mo2C/Al2O3 was accompanied by a leaching of the Mo component into solution. The carbide-based catalysts were characterised by a broader distribution of larger Au particles compared with the reference Au/Al2O3, which can be attributed to weaker Au/carbide interactions resulting in Au agglomeration during synthesis and activation. Nevertheless, the carbide systems delivered higher hydrogenation rates relative to Au/Al2O3. All the Au catalysts tested exhibited 100% selectivity to the target p-chloroaniline product in p-CNB hydrogenation. In the case of m-DNB, both nitro groups were hydrogenated to generate m-phenylenediamine as principal product for reaction over Au/Al2O3 whereas Au/Mo2C promoted the exclusive production of m-nitroaniline at low conversions. The results demonstrate a synergistic effect between Au and Mo2C that can be exploited in the cleaner production of commercially important aromatic amines.

AB - β-Mo2C and β-Mo2C/Al2O3 have been synthesised via temperature programmed carburisation and employed, for the first time, as supports for gold catalysts. 1% w/w Au/Mo2C and Au/Mo2C/Al2O3 were prepared by deposition–precipitation with urea and used to promote the gas phase hydrogenation of para-chloronitrobenzene (p-CNB) and meta-dinitrobenzene (m-DNB) where 1% w/w Au/Al2O3 served as a reference catalyst. The supports and supported Au catalysts have been characterised in terms of point of zero charge, temperature programmed reduction (TPR), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) measurements. Both Mo2C and Mo2C/Al2O3 exhibited hydrogenation activity that was significantly enhanced with the incorporation of Au. XPS and elemental analysis of Mo2C/Al2O3 revealed a lesser carbidic character and the presence of free surface carbon. Moreover, preparation of Au/Mo2C/Al2O3 was accompanied by a leaching of the Mo component into solution. The carbide-based catalysts were characterised by a broader distribution of larger Au particles compared with the reference Au/Al2O3, which can be attributed to weaker Au/carbide interactions resulting in Au agglomeration during synthesis and activation. Nevertheless, the carbide systems delivered higher hydrogenation rates relative to Au/Al2O3. All the Au catalysts tested exhibited 100% selectivity to the target p-chloroaniline product in p-CNB hydrogenation. In the case of m-DNB, both nitro groups were hydrogenated to generate m-phenylenediamine as principal product for reaction over Au/Al2O3 whereas Au/Mo2C promoted the exclusive production of m-nitroaniline at low conversions. The results demonstrate a synergistic effect between Au and Mo2C that can be exploited in the cleaner production of commercially important aromatic amines.

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